ES2256376T3 - DEVICE TO DETERMINE THE STATE OF AN EXHAUST GAS PURIFIER. - Google Patents

Abstract

A state determining apparatus for an exhaust gas purifier (6) arranged in an exhaust system of an internal combustion engine (1) to determine a state of said exhaust gas purifier (6) including an adsorbent (7 ) capable of adsorbing hydrocarbons and moisture in exhaust gases, including said state determination apparatus: a humidity sensor (22) disposed near said adsorbent in said exhaust system (2) to detect moisture in an exhaust pipe ( 4) of said exhaust system; temperature status detecting means (23) for detecting a temperature state (TW) in said exhaust system (2); and means for determining the state of adsorbent (25) to determine a state of said adsorbent (7) according to the humidity in the exhaust pipe (4) detected by said humidity sensor (22) and the temperature state in said system of leak detected by said temperature status detecting means (23).

Description

Apparatus for determining the status of a exhaust gas purifier.

Background of the invention Field of the Invention

The present invention generally relates to a state determination apparatus for a gas purifier of exhaust that purifies exhaust gases expelled from an engine internal combustion, and more specifically, to a determining device status for an exhaust gas purifier that purifies gases Exhaust adsorbing hydrocarbons contained in the gases of escape by an adsorbent.

Description of the prior art

One type of internal combustion engine is provided with an adsorbent arranged in its exhaust system to adsorb hydrocarbons in exhaust gases when starting the engine. He adsorbent has, for example, zeolite on its surface, of such so that hydrocarbons present in the exhaust gases enter pores of the zeolite and are adsorbed by the adsorbent when the hydrocarbons pass through the adsorbent. When the adsorbent is heated to a predetermined temperature or higher (for example, 100-250 ° C) by the exhaust gases, the adsorbent desorbs hydrocarbons once adsorbed that are recirculated to the Internal combustion engine using an EGR tube and the like. While the adsorption and desorption of hydrocarbons are repeated in the adsorbent as above, a long-term use of the adsorbent can lead to a gradually increasing amount of residual hydrocarbons that could not be desorbed, and to breakage of pores of the adsorbent. As a result, the adsorbent deteriorates, producing gradually degraded abilities to adsorb hydrocarbons in the adsorbent. When the combustion engine internal is launched in such a state, hydrocarbons not adsorbed by the adsorbent are emitted abroad. So, you have to determine the state of the adsorbent, in particular, its deterioration.

The applicant has proposed a deterioration determination apparatus to determine a deterioration of such adsorbent, for example, in published Japanese Patent Application No. 2001-323811. This deterioration determination apparatus takes advantage of a proportional relationship found between the adsorbent capacities of adsorbing hydrocarbons and moisture, and detects the humidity of exhaust gases that have passed through the adsorbent with a humidity sensor to determine the degraded adsorbent adsorbent capacities hydrocarbons and moisture, that is, the deterioration of the adsorbent. More specifically, the deterioration determination apparatus establishes a predetermined time required for a detected humidity of the humidity sensor to rise a predetermined value associated with a gradual increase in the humidity of the exhaust gases passing through the adsorbent, while the humidity in Exhaust gases are adsorbed by the adsorbent, after starting the engine, according to the starting humidity and the like, with reference to a normal adsorbent that has not been deteriorated, and measures the time that the detected humidity really takes to increase the value predetermined. Then, when the measured time is shorter than the predetermined time, it is determined that the adsorbent is impaired from the fact that the rate of increase of the detected humidity
is higher or the humidity detected begins to rise at a time earlier than when a normal adsorbent is used.

However, the apparatus for determining deterioration described above may not guarantee sufficient accuracy of determination of the deterioration of the adsorbent, because the humidity detected by the humidity sensor rises at an increasing rate different or at a different time depending on the state of exhaust system temperature when starting the combustion engine internal

More specifically, for example, when an engine Internal combustion starts cold, heat generated by exhaust is expelled by an exhaust system that has substantially the same temperature as the temperature in a boot environment (outside air temperature), so that the temperature of the exhaust gases is lower in one more position down the exhaust system. After when the temperature decreases to dew point (for example, 50-60ºC), the humidity of the exhaust gases begins  to condense and join on the inside surface of a tube of exhaust and the like, so that moisture in exhaust gases decreases further in a more downward position in the system escape. Such condensation occurs more, in an earlier time, and in an upward position in the exhaust system when the Exhaust system is at a lower temperature when starting. By For this reason, the humidity detected tends to have a lower rate increase because the adsorbent is supplied with exhaust gases with less humidity, that is, with less humidity when the Condensation occurs in an upward position of the adsorbent.  This trend is stronger when the exhaust system is at lower temperatures when the combustion engine starts internal

In addition, as described above, the adsorbent desorbs hydrocarbons when heated to a predetermined temperature or higher, and tends to have a higher performance of adsorbing hydrocarbons when the temperature is less than the temperature at which desorption begins (for example, 50 ° C) or lower. This trend also takes place in the moisture adsorption performance as well as the performance of hydrocarbon adsorption. Therefore, when the engine of combustion starts cold, the detected humidity increases by later time because a larger amount of moisture in gases Exhaust is adsorbed in the adsorbent when the temperature of the adsorbent having substantially the same temperature as the temperature in the exhaust system is lower.

As described above, while the detected humidity increases at a different rate and at a different time depending on a temperature state of the exhaust system at the start of the internal combustion engine, said deterioration determination apparatus simply establishes a time since the start-up as a parameter to determine a deterioration of the adsorbent, so that it only provides insufficient accuracy to determine the deterioration, and therefore there is room for improvement in this respect.
to.

EP-A-1132589 as prior art according to Art. 54 (3) and (4) EPC describes a temperature sensor 24 to detect a TTRS temperature of the adsorbent HC 16. However, the TTRS temperature of the adsorbent HC detected by temperature sensor 24 is used only for calculate a saturated absolute humidity DS (step 2, figure 4), and the calculated saturated absolute humidity DS is used only for establish a deterioration detection execution flag f_MCNDTRS (steps 5, 6 and 8 of Figure 3), that is, to determine  if the condition of execution for the determination of deterioration of the HC 16 adsorbent has been established or not. In addition, this document describes an intake air temperature sensor 27 for detect the intake air temperature TA. However, the intake air temperature TA is used only to determine if the moisture detection execution condition (step 106 of Figure 11) has been established or not.

Object and summary of the invention

The present invention has been made to solve the aforementioned problems, and an object of the invention is provide a state determination apparatus for a exhaust gas purifier that is able to determine with precision state of the exhaust gas purifier, which includes an adsorbent to adsorb hydrocarbons, including deterioration of the adsorbent, according to a temperature state of a system of exhaust in an internal combustion engine.

To achieve the previous object, the present invention provides a state determination apparatus for a exhaust gas purifier arranged in an exhaust system of an internal combustion engine to determine a state of the exhaust gas purifier including an adsorbent capable of adsorb hydrocarbons and moisture in exhaust gases. The apparatus of status determination is characterized by including a sensor moisture disposed near the adsorbent in the exhaust system to detect moisture in an exhaust pipe of the exhaust system; temperature status detecting means to detect a state of temperature in the exhaust system; and means of determining adsorbent state to determine a state of the adsorbent according to the moisture in the exhaust pipe detected by the humidity sensor and the temperature status in the exhaust system detected by the temperature status detecting means.

According to this state determination device For an exhaust gas purifier, the humidity sensor arranged near the adsorbent in the exhaust system detects a moisture in an exhaust pipe of the exhaust system, while the temperature status detecting means detect a state of temperature in the exhaust system. Then, the means of adsorbent status determination determine the state of the adsorbent according to the results of determinations. Since the ability of the adsorbent to adsorb hydrocarbons and moisture is in a proportional relationship, the humidity detected by the sensor humidity has a high correlation to hydrocarbons really adsorbed in the adsorbent. In addition, as mentioned previously, the humidity detected by the humidity sensor increases at a different rate and at a different time depending on the state of temperature in the exhaust system. Therefore, when the temperature state in the exhaust system is used as a parameter in addition to the humidity inside the exhaust pipe to perform the state determination, the state of the adsorbent can be determined accurately, including adsorption and desorption of hydrocarbons in the adsorbent, deterioration of the adsorbent, and analogues, reflecting at the same time the actual gas temperature of escape in the result of the determination.

Preferably, the apparatus for determining state for an exhaust gas purifier also includes means Calorie calculation to calculate the calories supplied from the internal combustion engine to the exhaust system after start the internal combustion engine where the means of adsorbent status determination also determine the status of the adsorbent also according to the calories calculated by the means Calorie calculation.

According to this preferred embodiment of the apparatus of status determination, the means of calculating calories calculate the calories supplied by the internal combustion engine at exhaust system after starting the combustion engine internal, and the means of determining adsorbent status they also determine the state of the adsorbent also according to the Calories calculated by means of calorie calculation. For the so much is possible to determine more exactly the state of the adsorbent reflecting also the states of the system of escape and a change in temperature (rise) of the adsorbent after of the start in the result of the determination. Preferably, the state determination apparatus for a gas purifier Exhaust also includes threshold determination means for determine a threshold based on the state of temperature in the system Exhaust detected at the time of starting the combustion engine internal, where calorie calculation means include means of Calculation of cumulative fuel injection quantity for calculate an amount of cumulative fuel supplied to internal combustion engine since its start as calories, and the adsorbent state determination means determine the adsorbent status based on a comparison result between the amount of fuel accumulated since engine start internal combustion and the threshold when an amount of change of value detected by the humidity sensor after starting the internal combustion engine exceeds a predetermined value settled down.

According to this preferred embodiment of the apparatus of status determination, the state of the adsorbent can be determine at an appropriate time in which an amount of change of the value detected by the humidity sensor after starting of the internal combustion engine exceeds the predetermined value established, that is, to which the moisture in the exhaust pipe increases (rises) sufficiently when adsorption to the adsorbent is saturate gradually. In addition, the state of the adsorbent is determined based on the result of a comparison of the amount of accumulated fuel supplied to the internal combustion engine from the start to the time when the moisture in the exhaust pipe sufficiently increases with the threshold determined by the means of threshold determination. This threshold reflects the status of exhaust system temperature at engine start internal combustion, while the amount of fuel accumulated Indicates the calories given to the exhaust system after starting. Therefore, determining the state of the adsorbent based on the result of comparing the amount of fuel accumulated with the threshold, the state of the adsorbent can be determined with more accuracy, also reflecting the actual temperatures of the system Exhaust and adsorbent at the time of starting the combustion engine internal, and after startup, in the result of the determination. In addition, since the amount of fuel is a known control parameter for the internal combustion engine, the calories given to the exhaust system can be calculated easily by simply accumulating the amount of fuel from the internal combustion engine start.

Preferably, the apparatus for determining state for an exhaust gas purifier also includes means room temperature detectors to detect a temperature environment around the humidity sensor; and means of calculation of relative humidity to calculate a relative humidity of gases from leakage of a humidity sensor outlet according to the temperature environment detected.

According to this preferred embodiment of the apparatus of determination of state, since the humidity of the gases of Exhaust is calculated from the humidity sensor output according to the ambient temperature around the humidity sensor, it is possible properly find the relative humidity with compensation of temperature. In addition, the state of the adsorbent can be determined appropriately according to the relative humidity found in this way.

Preferably, in the determining apparatus status for an exhaust gas purifier, the sensor moisture is disposed in a downward position of the adsorbent in the exhaust system

According to this preferred embodiment of the apparatus of status determination, since the humidity sensor is arranged in a downward position of the adsorbent in the system Exhaust, the humidity sensor can detect the humidity of gases Exhaust that have passed through the adsorbent after starting the Internal combustion engine. Thus, the humidity that reflects a state adsorbed hydrocarbon in the adsorbent can be detected during the operation of the internal combustion engine, to accurately determine the state of the adsorbent.

Preferably, in the determining apparatus status for an exhaust gas purifier, the means of adsorbent status determination determine the state of the adsorbent after a combustion engine stop internal

According to this preferred embodiment of the apparatus of status determination, since the state of the adsorbent is determines after stopping the internal combustion engine, the state of the adsorbent can be determined without checking the moisture in the exhaust pipe with the humidity sensor throughout moment, unlike the determination of adsorbent status performed during the operation of the internal combustion engine. He adsorbent status can be determined in this way by following reasons. When the internal combustion engine stops, the heated adsorbent cools gradually, and therefore adsorbs surrounding moisture. Then, when the adsorbent adsorbs incrementally the saturation humidity, the humidity around the adsorbent remains substantially constant, that is, in the regime status The humidity in the regime state reflects the state of the adsorbent, in particular a degree of deterioration. Specifically, a greater degree of deterioration of the adsorbent indicates that the adsorbent has a lower adsorption performance of moisture, so that the adsorbent does not adsorb much moisture surrounding. As a result, the humidity around the adsorbent tends to be higher compared to around a normal adsorbent Therefore, it is possible to determine the status of the adsorbent detecting moisture around the adsorbent after Stop the internal combustion engine. In addition, since the status determination only requires moisture detection in the exhaust pipe that remains in the regime state, a sensor of humidity does not have to have high sensitivity, so that you can use a reasonable humidity sensor, thereby reducing the General device cost.

Preferably, in the determining apparatus status for an exhaust gas purifier, the means of adsorbent status determination determine the state of the adsorbent within a predetermined period after stopping the Internal combustion engine.

According to this preferred embodiment of the apparatus of status determination, the state of the adsorbent can be accurately determined by executing the status determination within the predetermined period after stopping the engine internal combustion, that is, within a period in which the determination of adsorbent status can be performed properly. As described above, when the internal combustion engine, the adsorbent adsorbs moisture surrounding when the exhaust system cools, putting the moisture around the adsorbent in the regime state. When it takes a long time after stopping the combustion engine internal, the moisture inside the exhaust pipe, which has been in the regime state, gradually converges to external moisture because The exhaust system is in communication with the outside. For the therefore, the state of the adsorbent can be determined appropriately and accurately executing the status determination while the moisture inside the exhaust pipe remains in the regime state until it begins to converge to external moisture.

Preferably, in the determining apparatus status for an exhaust gas purifier, the sensor moisture is disposed in an upward position of the adsorbent in the exhaust system.

According to this preferred embodiment of the apparatus of status determination, the humidity sensor is spaced from the lowermost end of the exhaust system in communication with the outside a greater distance than when the humidity sensor is arranged in a downward position of the adsorbent, so that the humidity sensor can be prevented is adversely affected by a disturbance such as influence of outside air when the combustion engine is stopped internal, for example, a gas exchange between the atmosphere inside the exhaust pipe near the humidity and air sensor Exterior. In this way, the determination of the state of the adsorbent It can be done properly and accurately.

Preferably, the apparatus for determining state for an exhaust gas purifier also includes means operating condition detectors to detect if the engine internal combustion is put into operation or not in a condition default operation before the combustion engine stops internal, where the means of determining adsorbent status determine the state of the adsorbent when the detecting means of operating condition detect that the internal combustion engine is puts into operation in the default operating condition before the internal combustion engine stops.

According to this preferred embodiment of the apparatus of status determination, adsorbent status determination it is done when the internal combustion engine is put on operation in the default operating condition before Stop the internal combustion engine. In general, the amount of moisture contained in the exhaust gases depends on the condition Operation of the internal combustion engine. Therefore the state of the adsorbent can be determined exactly after stopping the internal combustion engine defining the operating condition predetermined as an operating condition in which gases from exhaust contain an adequate amount of moisture to determine the state of the adsorbent.

Preferably, in the determining apparatus status for an exhaust gas purifier, the condition default operating internal combustion engine is a condition in which an air / fuel mixture supplied to the Internal combustion engine is at an air / fuel ratio close to the stoichiometric air / fuel ratio during internal combustion engine operation.

According to this preferred embodiment of the apparatus of determination of status, determination of impairment of Adsorbent is made after stopping the internal combustion engine during an operation near the stoichiometric ratio of air / fuel When the internal combustion engine is set to operation near the stoichiometric ratio of air / fuel, exhaust gases contain an amount relatively large humidity without large variations, so that the ambient humidity around the humidity sensor after stopping the engine is also relatively high without large variations, suitable for determining the deterioration of the adsorbent. Thus, the determination of impairment made in such condition can provide a more accurate determination on whether The adsorbent has deteriorated.

Preferably, in the determining apparatus status for an exhaust gas purifier, the status of exhaust system temperature is the water temperature of cooling at the start of the internal combustion engine.

According to this preferred embodiment of the apparatus of status determination, the temperature of the cooling water in the internal combustion engine when starting can be used properly as a parameter indicative of the state of temperature in the exhaust system. In addition, since the engine of internal combustion is typically provided with a sensor water temperature to detect the water temperature of cooling, the existing water temperature sensor can be use to detect the operating condition, thereby performing the Temperature sensing means at a low cost.

Preferably, in the determining apparatus status for an exhaust gas purifier, the means of adsorbent status determination include means of Determination of adsorbent deterioration to determine a deterioration of the adsorbent as the state of the adsorbent.

As described above, an adsorbent deteriorated has less ability to absorb moisture as well as hydrocarbons, so that the deterioration of the adsorbent can be determine by detecting moisture around the adsorbent. For the therefore, according to the preferred embodiment of the determining apparatus status, the deterioration of the adsorbent can be determined with precision by the state determination technique of the present invention so far described, reflecting at the same time satisfactorily the temperature status in the exhaust system of the internal combustion engine in the result of the determination.

Preferably, in the determining apparatus status for an exhaust gas purifier, the adsorbent includes zeolite

According to this preferred embodiment of the apparatus of determination of state, zeolite adsorbs moisture as well as hydrocarbons, and there is a high correlation between the capacities of the zeolite to adsorb both components, so that the advantages and effects described so far can be achieved by applying the present invention The zeolite can implement an adsorbent of excellent heat resistance and that is less susceptible to deterioration, compared, for example, with silica gel, carbons assets or analogues when used as the adsorbent.

Brief description of the drawings

Figure 1 is a diagram that illustrates in general an internal combustion engine in which a determining apparatus status for an exhaust gas purifier is applied according to a First embodiment of the present invention.

Figure 2 is a cross-sectional view. enlarged illustrating an adsorption device of hydrocarbon

Figure 3 is a flow chart illustrating a routine to determine whether or not a determination of deterioration of an adsorbent.

Figure 4 shows a table to calculate a relative humidity VHUMD according to a THCM ambient temperature and a VRST sensor resistance value.

Figure 5 is a table of thresholds of Determination of impairment showing the relationship between a TW engine water temperature at engine start and threshold of determination of deterioration of adsorbent TRSDT.

Figure 6 is a flow chart illustrating a routine to determine the deterioration of the adsorbent based on a relative humidity VHUMD.

Figure 7 is a time diagram showing an exemplary transition of a relative humidity VHUMD detected by a humidity sensor located down and the amount of injection of sum_tout accumulated fuel from engine start.

Figure 8 is a flow chart illustrating a routine to determine whether or not a determination of deterioration of an adsorbent in a second embodiment.

Figure 9 is a table of thresholds of Determination of impairment showing the relationship between a TW engine water temperature at engine start and threshold of determination of deterioration of adsorbent TRSDTV.

Figure 10 is a flow chart illustrating a routine to determine the deterioration of the adsorbent based on a VRST sensor resistance value.

Figure 11 is a time diagram showing an exemplary transition of the VRST sensor resistance value that it is a detection value of a humidity sensor located towards below, and the amount of fuel injection accumulated sum_tout Engine start

Figure 12 is a flow chart illustrating a routine to determine the deterioration of the adsorbent, which Run after stopping the engine.

And Figure 13 is a time diagram that shows an exemplary transition of a detected ambient humidity by a humidity sensor located up after stopping the motor (in an upper portion), and a time diagram showing an exemplary transition of an engine water temperature after stopping the engine (in a lower portion).

Detailed description of the embodiment

A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings. Figure 1 illustrates an internal combustion engine in which a state determination apparatus for an exhaust gas purifier is applied according to a first embodiment of the present invention. An exhaust system 2 of the engine 1 has an exhaust pipe 4 connected to the engine 1 by an exhaust manifold 3. A catalyst 6 having two three-way catalysts 5, and a hydrocarbon adsorber 7 for adsorbing hydrocarbons are provided to halfway in the exhaust pipe 4 as an exhaust gas purifier to purify exhaust gases. The two three-way catalysts 5 of the catalyst 6 are arranged side by side along the exhaust pipe 4, and purify harmful substances (hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NOx)) in Exhaust gases that pass through catalyst 6 by oxidation-reduction catalytic actions, when heated to a predetermined temperature (for example, 300 ° C) or higher and activated
go.

The hydrocarbon adsorber 7 is arranged to turn in a downward position of catalyst 6 in the tube of Exhaust 4, and is planned to reduce the amount of hydrocarbons emitted into the atmosphere adsorbing hydrocarbons in exhaust gases for an initial period (for example, for approximately 30 40 seconds after starting) of engine 1 in a cold state in that the three-way catalysts 5 have not been activated. How I know illustrated in figures 1 and 2, the hydrocarbon adsorber 7 is coupled to a downward end of catalyst 6 by means of an escape passage switch 8. The adsorber of hydrocarbons 7 includes a substantially cylindrical housing 11; a bypass exhaust pipe 12 disposed within the case 11; and a cylindrical adsorbent 16 disposed midway in the tube bypass exhaust 12 to adsorb hydrocarbons in the gases of Exhaust that are introduced into the bypass exhaust pipe 12.

As illustrated in Figure 2, box 11 has its upward end divided into two holes, that is, one upper and one lower 11a, 11 b. The top hole 11a is in communication with a main step 13 which has a section transverse annular and is formed between the box 11 and the tube of bypass exhaust 12, while the bottom hole 11b is in communication with a bypass step 14 which is a space inside of the bypass exhaust pipe 12.

The bypass exhaust pipe 12 has its upward end connected to an inner surface of the bottom hole 11b of box 11, and one end located down connected to an inner surface of one end located towards below the box 11, respectively, in an air tight state. The bypass exhaust pipe 12 is formed with a plurality of elongated communication holes 12a (for example, five) in one descending end portion in the circumferential direction a equal intervals, such that the end located down from main step 13 be in communication with the located end down bypass step 14 through these holes of communication 12a.

Adsorbent 16 consists of a honeycomb core (not represented), made of a metal, which carries zeolite in its surface, and has the property of adsorbing moisture as well as hydrocarbons When the exhaust gases introduced in the passage of bypass 14 pass through adsorbent 16, hydrocarbons and moisture in Exhaust gases are adsorbed by zeolite. The zeolite, which It has high heat resistance properties, adsorbs hydrocarbons at low temperatures (for example, below 100 ° C), and desorbs hydrocarbons once adsorbed a predetermined temperature or higher (for example, 100-250 ° C). Then, the desorbed hydrocarbons are make motor 1 of the hydrocarbon adsorber 7 to be recirculated through an EGR tube 17 and an inlet tube 1a, and they are burned by engine 1.

The escape passage switch 8 is provided to selectively switch the exhaust passage down from catalyst 6 to main step 13 or bypass step 14 according to an activated state of the three-way catalysts 5. The exhaust passage switch 8 includes a coupling tube substantially cylinder 18; and a pivotable switching valve 15 arranged in the coupling tube 18. The valve switching 15 is moved by a switching valve exciter 19 (see Figure 1) which is controlled by an ECU 25, described later, to switch the passage of exhaust gases to the passage main 13 when present in a position indicated with continuous lines in figure 2 and to commute the passage of gases from escape to bypass passage 14 when present in a position indicated with two dotted lines and stripe.

As described above, the EGR 17 tube is coupled between the coupling tube 18 and the inlet tube 1a from engine 1 to recirculate a portion of exhaust gases to the engine 1, and an EGR 20 control valve is disposed midway in tube EGR 17. The control valve EGR 20 is controlled by the UEC 25 to activate and stop the EGR and control a quantity of EGR

In the previous configuration, the exhaust gas passage is switched to the bypass passage 14 by the exhaust passage switch 8 immediately after a cold start of the engine 1, thereby resulting in the exhaust gases passing through the catalyst 6 to the bypass passage 14. Exhaust gases are emitted into the atmosphere after the hydrocarbons in the exhaust gases have been adsorbed by adsorbent 16. Then, when it is determined that the hydrocarbons have been adsorbed by adsorbent 16, The exhaust passage is switched to the main passage 13 to conduct the exhaust gases to the main passage 13 through the coupling tube 18 for emission into the atmosphere. In addition, when the EGR control valve 20 is opened to operate the EGR, a portion of the exhaust gases is recirculated to the inlet pipe 1a by the bypass passage 14 and the EGR tube 17 as an EGR gas. The hydrocarbons
desorbed bonds of adsorbent 16 are sent to the inlet tube 1a by the EGR gas and burned by the engine 1.

A humidity sensor located down 22 is attached to the box 11 of the hydrocarbon adsorber 7 in a position down the adsorbent 16 facing the bypass passage 14. The humidity sensor located down 22 is used to determine the state, mainly deterioration, of adsorbent 16 during the engine operation 1. The humidity sensor located down 22 includes a sensor element 22a (see Figure 2) composed of a porous body, for example, made of alumina, titania or the like, and detects moisture, taking advantage of the characteristic that its value of resistance varies according to the amount of moisture adsorbed in the pores of the sensor element 22a. The humidity sensor located towards below 22 sends a detection signal indicative of a value of VRST resistor of sensor element 22a to ECU 25. A sensor of ambient temperature 21 (ambient temperature detecting means) composed of a thermistor or analogs is also arranged nearby of the sensor element 22a to detect a THCM ambient temperature near the sensor element 22a and send a detection signal indicative of the ambient temperature THCM at ECU 25.

A humidity sensor located upwards 30 it is also attached to the box 11 of the hydrocarbon adsorber 7 in an upward position of adsorbent 16 facing the passage of shunt 14 to determine the state of adsorbent 16 during a inoperative state of the engine 1. The humidity sensor located towards top 30, which is similar to the humidity sensor located down 22, sends a detection signal indicative of a value of VRST2 resistance of a sensor element 30a to the ECU 25. A sensor ambient temperature 31 (temperature sensing means ambient) is also arranged near sensor element 30a for detect the THCM2 ambient temperature near the sensor element 30a and send a temperature indicative detection signal THCM2 environment to ECU 25.

A proportional ratio sensor of air / fuel (referred to below as the "LAF sensor") 32 it is further arranged in an upward position of the catalyst 6 on the exhaust pipe 4. The LAF 32 sensor linearly detects the oxygen concentration in the exhaust gases (ratio air / fuel) and sends the air / fuel ratio detected, it is that is, a VLAF detection value, to ECU 25. The value of VLAF detection of the LAF 32 sensor is set lower when the oxygen concentration is lower, that is, the ratio Air / fuel is richer.

A motor water temperature sensor 23 (temperature status detecting means) including a thermistor or the like, and a draft angle sensor 24 are attached to the engine body 1. The engine water temperature sensor 23 detects the water temperature of the TW motor, which is the temperature of cooling water circulating within a block of cylinders of engine 1, and sends a detection signal indicative of the water temperature of the TW motor to ECU 25. The sensor draft angle 24, on the other hand, sends a CRK signal and a signal TDC, which are pulse signals, at ECU 25 each draft angle default when the crankshaft, not shown, of the engine 1. An intake pressure sensor 26 is attached to the tube of inlet 1a to detect an absolute pressure PB inside the tube of input 1a and send a signal indicating the pressure absolute PB to ECU 25. An alarm lamp 27 is connected in addition to ECU 25 to generate an alarm by lighting when determines that absorbent 16 is damaged. ECU 25 also receives a detection signal from a temperature sensor ambient 33 indicative of an ambient temperature TA as a temperature outside engine 1 and exhaust pipe 4.

In this embodiment, the ECU 25 functions as a adsorbent state determination means, means of Calorie calculation, threshold determination means, some means for calculating the amount of fuel accumulated, means of relative humidity calculation, and means of determining adsorbent deterioration. The ECU 25 is based on a microcomputer that It includes an I / O interface, a CPU, a RAM, a ROM and the like. The detection signals of said sensors such as the sensor downward humidity 22 are introduced into the CPU after be converted A / D and reconstituted in the I / O interface. CPU controls a Tout fuel injection time for an injector 1b corresponding to each of a plurality of cylinders of the motor 1, the switching valve exciter 19, and the valve EGR 20 control according to a control program, tables and analogues stored in ROM in response to detection signals above, and determines the state, that is, the deterioration of the adsorbent 16.

The processing to determine the deterioration of the adsorbent 16 will be described below with reference to the Figures 3 to 7. Figure 3 illustrates a routine to determine if executes or not a determination of deterioration of adsorbent 16. This Routine runs only once immediately after start the engine 1.

First, in this routine, in step 1 (called "S1" in the figure. The same applies to the following description) it is determined whether a termination flag of desorption F_HCPG is or not "1", which indicates that hydrocarbons have been completely desorbed from adsorbent 16 during the preceding operation. If the result of the determination in step 1 it is NO, that is, when hydrocarbons have not been desorbed during the preceding operation, ECU 25 puts "0" an enable flag for determining deterioration F_MCNDTRS (step 2), assuming it is not establish conditions to execute a routine to determine the deterioration of adsorbent 16 because the remaining hydrocarbons in the adsorbent 16 prevent a correct determination of the deterioration of the adsorbent 16, followed by the completion of the routine.

On the other hand, if the result of the determination in step 1 is YES, indicating that the hydrocarbons have been desorbed during the preceding operation, the routine passes to step 3, where it is determined if the engine water temperature TW is or is not equal to or greater than its lower limit value TWTRSL (for example, 0 ° C) and equal to or lower than its upper limit value TWTRSH (for example, 50 ° C). If the result of the determination in step 3 is NO, that is, when the water temperature of the TW motor at engine 1 start is out of a defined predetermined range for the upper and lower limit values TWTRSL / TWTRSH, ECU 25 set the enable determination flag to "0" deterioration F_MCNDTRS (step 2) in the event that they have not been established conditions to execute the routine to determine the deterioration of adsorbent 16, as is the case with desorption incomplete hydrocarbons, followed by the termination of the routine.

On the other hand, if the result of the determination in step 3 is YES, indicating that the temperature of the TW motor water is within the predetermined range, ECU 25 set the deterioration determination enable flag F_MCNDTRS to "1" (step 4), assuming they are established conditions to execute the routine to determine the deterioration of the adsorbent 16. Next, the relative humidity VHUMD detected by the humidity sensor located down 22 at that time set as an initial value for a minimum value VHUMD_MIN (step 5) and a preceding value VHUMD_PRE (step 6), respectively, of the relative humidity VHUMD. The relative humidity VHUMD is calculated at from a table represented in figure 4 according to a value of VRST sensor resistance detected by the humidity sensor located down 22.

The table represented in figure 4 is formed for nine tables corresponding to the ambient temperature THCM, and Each table is set in such a way that the relative humidity VHUMD is lower when the VRST sensor resistance value is higher. In addition, between the tables, the relative humidity VHUMD is higher when THCM ambient temperature is lower. A table corresponding to THCM ambient temperature detected by the temperature sensor environment 21 is selected from these tables, and a search in a table corresponding to the resistance value of VRST sensor detected by the humidity sensor located down 22 to calculate the relative humidity VHUMD. When the temperature THCM environment has a value between tables, the relative humidity VHUMD is calculated by an interpolation. Finding relative humidity VHUMD in this way, the relative humidity VHUMD can be calculated appropriately for compensated temperature exhaust gases.

Next, the routine goes to step 7, where a table of deterioration determination thresholds is sought (later referred to as the "TRSDT table") for the adsorbent 16 shown in Figure 5 according to the water temperature of the TW engine to calculate a TRSDT impairment determination threshold (threshold) to determine the deterioration of adsorbent 16, described later, followed by the completion of the routine.

As depicted in figure 5, in the table TRSDT, the TRSDT impairment determination threshold is set to a first default trsdt1 when the water temperature TW motor is lower than a first predetermined temperature tw1 (for example, 0 ° C), and at a second predetermined value trsdt2 (trsdt1> trsdt2) when the engine water temperature TW exceeds a second predetermined temperature tw2 (for example 40 ° C) higher than the first predetermined temperature tw1. In addition, when the TW engine water temperature is between two predetermined temperatures tw1, tw2 (tw1 \ leq TW \ leq tw2), the TRSDT impairment determination threshold is set to a larger value when the TW engine water temperature is Minor.

Figure 6 illustrates a routine for determining the deterioration of adsorbent 16, executed according to the result of the determination made by the routine in said figure 3. This routine every default time is executed (for example, every 100 ms). In first, it is determined whether the enable flag of Determination of impairment F_MCNDTRS is or is not "1" (step 11). Yes the result of the determination in step 11 is NO, showing that the conditions for running a routine for determine the deterioration of adsorbent 16, the routine is terminated without Additional processing

On the other hand, if the result of the determination in step 11 is YES, showing that they have been established the conditions to execute a routine to determine the deterioration of adsorbent 16, it is determined whether the relative humidity VHUMD calculated from a current detection value provided by the humidity sensor located down 22 is or not less than the preceding value VHUMD_PRE (step 12). If he result of the determination in step 12 is YES, that is, VHUMD <VHUMD_PRE, ECU 25 puts the relative humidity VHUMD in said time as a minimum value VHUMD_MIN (step 13). This way, the minimum value VHUMD_MIN is updated at all times when the relative humidity VHUMD is less than its previous value, so that the minimum value VHUMD_MIN indicates a minimum value immediately before the relative humidity VHUMD begins to increase (see time t0 in figure 7). If the result of the determination in step 12 is NO, or after executing step 13, the routine goes to step 14, where ECU 25 displaces moisture relative current VHUMD to the preceding value VHUMD_PRE.

Next, it is determined whether the humidity relative VHUMD is or not greater than the sum of the minimum value VHUMD_MIN and a predetermined increasing determination value VHUMD_JUD (for example, 10%) (step 15). If the result of the determination in the step 15 is NO, UEC 25 puts an establishment flag increasing FHUML2H to "0" (step 16), assuming that the relative humidity VHUMD has not risen sufficiently, followed by Routine completion.

On the other hand, if the result of the determination in step 15 is YES, showing that VHUMD \ text {>} is set
VHUMD_MIN + VHUMD_JUD, that is, when the relative humidity VHUMD rises from the minimum value VHUMD_MIN beyond the increasing determination value VHUMD_JUD (at time t1 in Figure 10), the ECU 25 sets the increasing establishment flag FHUML2H to "1" (step 17), in the event that the relative humidity VHUMD has risen sufficiently and is now rising steadily.

Next, the routine goes to step 18, where it is determined whether a cumulative fuel injection amount sum_tout (amount of fuel accumulated) is or not less than TRSDT impairment determination threshold calculated in said step 7 in figure 3. This amount of cumulative fuel injection sum_tout indicates an aggregate of fuel injection time Tout of the injector 1b in each cylinder of the engine 1 starter, and indicates the calories given by engine 1 to exhaust system 2 since its start. Therefore, a greater amount of injection of cumulative fuel sum_tout indicates more calories given to adsorbent 16. On the other hand, adsorbent 16 tends to have a high adsorption performance at low temperatures and present a lower adsorption performance when temperature rises. The relative humidity VHUMD increases when the temperature increases by a certain degree Therefore, if the result of the determination in step 18 is YES, that is, when sum_tout <TRSDT, ECU 25 determines that adsorbent 16 is impaired in the case of that the relative humidity VHUND has risen before although the adsorbent 16 don't get enough calories to make the humidity rise relative VHUMD, and sets an FTRSDT deterioration flag to "1" (step 19) to indicate that adsorbent 16 is damaged.

On the other hand, if the result of the determination in step 18 is NO, that is, when sum_toutTRSDT, ECU 25 determines that adsorbent 16 is not impaired in the assumption that the relative humidity VHUMD increases right after adsorbent 16 receives enough calories, and puts the indicator of deterioration F_TRSDT to "0" (step 20).

In step 21 after step 19 or 20, the ECU 25 puts an impairment determination enable flag F_MCNDTRS to "0" in response to termination of the Determination of deterioration for adsorbent 16, followed by Routine completion.

As described above in detail, according to the previous embodiment, the increasing determination value VHUMD_JUD is used to determine if the relative humidity VHUMD down the adsorbent 16 has risen or not after starting of engine 1, and the amount of fuel injection accumulated sum_tout from the beginning to the increase, that is, the calories given to adsorbent 16 are compared with the threshold value of determination of TRSDT deterioration to determine a deterioration of adsorbent 16, of so that the deterioration determination can be made with accuracy according to a temperature state of the exhaust system at start and after engine start 1. In addition, as described above in connection with figure 5, the threshold value of Determination of impairment TRSDT becomes larger when the TW engine water temperature at startup is lower. In others terms, the TRSDT impairment determination threshold value is it gets bigger the more calories are required to increase the temperature of adsorbent 16, so that the determination of deterioration for adsorbent 16 can be done more appropriately by determination by comparing in step 18 in the figure 6.

A second one will be described below. embodiment with reference to figures 8 to 11. Unlike the first embodiment, the second embodiment uses the value of VRST sensor resistance, which is the sensor detection value of moisture located down 22, without converting it to moisture relative HVUMD. The VRST sensor resistance value has a higher value when the humidity of the exhaust gases is lower. In other terms, the resistance value of VRST sensor presents behaviors completely inverse to relative humidity VHUMD in the first embodiment in terms of the magnitude and increase decrease. Specifically, the relative humidity VHUMD rises After starting engine 1 as described above, while the VRST sensor resistance value drops as described below (see figure 11). In the description next, the processing parts similar to the first realization will be described briefly.

Figure 8 illustrates a routine to determine if impairment determination is performed or not, corresponding to the routine illustrated in Figure 3 in the first embodiment. How I know illustrated in figure 8, in this routine, it is first determined whether a desorption termination flag F_HCPG is "1" or not (step 31). If the result of the determination in step 31 is NO, UEC 25 sets an enable flag for determining deterioration F_MCNDTRS to "0" (step 32), assuming that the hydrocarbons have not been desorbed during operation above, so that the conditions for run a routine to determine the deterioration of adsorbent 16, followed by the completion of the routine. On the other hand, if the result of the determination in step 31 is YES, it is determined whether the water temperature of the TW motor is equal to or greater than its TWTRSL lower limit value (for example, 0 ° C) and equal to or less than its upper limit value TWTRSH (for example, 50 ° C) (step 33). If he result of the determination in step 33 is NO, that is, when TW motor water temperature is out of range default defined by upper and lower limit values TWTRSL / TWTRSH, the UEC 25 sets the enable flag of Determination of deterioration F_MCNDTRS to "0" (step 32) in the assumption that the conditions for execute the routine to determine the deterioration of adsorbent 16, followed by the completion of the routine.

On the other hand, if the result of the determination in step 33 is YES, indicating that the temperature of the TW motor water is within the predetermined range, ECU 25 set the deterioration determination enable flag F_MCNDTRS to "1" (step 34), and set the resistance value of VRST sensor out of the humidity sensor located down 22 in said time as respective initial values for a maximum value VRST_MAX (step 35) and a preceding value VRST_PRE (step 36), respectively. Then, the routine goes to step 37, where ECU 25 look for a table of impairment determination thresholds (referred to below as the "TRSDTV table") represented in Figure 9 to calculate the relative humidity TRSDTV, followed by the Routine completion.

The TRSDTV table shown in Figure 9 corresponds to the TRSDT table represented in figure 5 in the First realization Therefore, in the TRSDTV table, the value TRSDTV deterioration determination threshold of adsorbent 16 se also set according to the water temperature of the TW motor of as follows. The TRSDTV impairment determination threshold is set to a first default trsdtv1 when the TW motor water temperature is lower than a first default temperature tw1 (for example, 0 ° C), and at one second default value trsdtv2 (trsdtv1> trsdtv2) when the TW motor water temperature exceeds a second temperature default tw2 (for example 40 ° C). Also, when the TW motor water temperature is between the two temperatures default tw1, tw2 (tw1 \ leq TW \ leq tw2), the threshold of Determination of impairment TRSDTV is set to a larger value when the water temperature of the TW engine is lower.

Figure 10 illustrates a routine to determine a deterioration of adsorbent 16 based on the resistance value of VRST sensor of the humidity sensor located down 22, which executed according to the result of the determination made by the routine illustrated in figure 8. The routine in figure 10 corresponds to the routine illustrated in figure 6 in the first realization. In this routine, it is first determined whether the flag of impairment determination enable F_MCNDTRS is or not "1" (step 41). If the result of the determination in step 41 is NO, that is, when the conditions have not been established to execute the impairment determination, this routine is terminated No additional processing. On the other hand, if the result of the determination in step 41 is YES, that is, when they have established the conditions to execute the determination of deterioration, it is determined whether the VRST sensor resistance value detected by the humidity sensor located down 22 in the real time is or not greater than the previous value VRST_PRE (step 42).

If the result of the determination in step 42 is YES, that is, VRST <VRST_PRE, ECU 25 sets the value of VRST sensor resistance at that time as a maximum value VRST_MAX (step 43). In this way, the maximum value VRST_MAX is updated at all times when the sensor resistance value VRST is greater than its previous value, so that the maximum value VRST_MAX indicates a maximum value immediately before the value VRST sensor resistance detected by the humidity sensor located down 22 begin to rise (see time t0 in the figure 11). If the result of the determination in step 42 is NO, or after executing step 43, the routine goes to step 44, where ECU 25 displaces the VRST current resistance value sensor to the previous value VRST_PRE.

Next, it is determined whether the value of VRST sensor resistance is or not less than the sum of the value maximum VRST_MAX and a default drop determination value VRST_JUD (for example, 30% of VRST_MAX) (step 45). If the result of the determination in step 45 is NO, ECU 25 puts a F_RSTL2H drop setting flag to "0" (step 46), assuming that the VRST sensor resistance value does not has fallen sufficiently, followed by the termination of the routine.

On the other hand, if the result of the determination in step 45 is YES, showing that VRST> VRST_MAX-VRST_JUD is set, that is, when the VRST sensor resistance value falls from the maximum VRST_ value
MAX the fall determination value VRST_JUD or more (at time t1 in Figure 11), the ECU 25 sets the fall setting flag F_RSTL2H to "1" (step 47), assuming the resistance value VRST sensor has dropped sufficiently and is now falling steadily.

Next, the routine goes to step 48, where it is determined whether a cumulative fuel injection amount sum_tout of engine 1 start is or not less than the threshold of TRSDTV impairment determination calculated in said step 37 in the Figure 8. If the result of the determination in step 48 is YES, that is, when sum_tout <TRSDTV, the ECU 25 determines that the adsorbent 16 is impaired on the assumption that the value of VRST sensor resistance has fallen before although adsorbent 16 don't get enough calories to make the value of VRST sensor resistance drop, and set the deterioration signaling FTRSDT to "1" (step 49).

On the other hand, if the result of the determination in step 48 is NO, that is, when sum_tout \ geqTRSDT, ECU 25 determines that adsorbent 16 does not is impaired on the assumption that the resistance value of VRST sensor falls just after adsorbent 16 receives enough calories, and sets the FTRSDT deterioration flag to "0" (step 50). Then, in the next step 51, the ECU 25 puts an impairment determination enable flag F_MCNDTRS to "0" in response to termination of the Determination of deterioration of adsorbent 16, followed by Routine completion.

As described above in detail, according to the second embodiment, the determination of deterioration can be do precisely with respect to adsorbent 16 according to a state of exhaust system temperature at startup and after startup of the motor 1, as is the case of the first embodiment.

A third will be described below. embodiment of the present invention with reference to figures 12 and 13. In the third embodiment, the determination of impairment is does with respect to adsorbent 16 using the humidity sensor up 30 after stopping the engine 1. It must be note that the relative humidity VHUMD detected by the sensor upward humidity 30 is compensated with respect to the temperature based on the THCM2 ambient temperature detected by the ambient temperature sensor 31 similar to previous embodiments.

Figure 12 is a flow chart illustrating a routine to determine a deterioration of adsorbent 16, which is runs after stopping the engine 1. Determination of deterioration It is done based on these policies. Specifically, the adsorbent 16 incrementally adsorbs moisture when the heated adsorbent 16 gradually cools after stopping the engine 1. The adsorbent 16 is determined with respect to deterioration based on moisture around adsorbent 16 (hereinafter simply called the "ambient humidity") within the bypass passage 14 which remains substantially at a constant value when the adsorbent 16 is saturated.

Determination of impairment is made specifically when UEC 25 is re-started by a idle timer that has set a time default (for example, two hours) after the course of default time after stopping engine 1 (time t2 in the figure 13). Adsorbent 16 is determined with respect to deterioration based on the ambient humidity VHUMD which is the relative humidity detected by the humidity sensor located upwards 30. How to illustrated in figure 12, it is first determined in step 61 if the desorption termination flag F_HCPG is or is not "1". Yes the result of the determination in step 61 is NO, that is, when the desorption is not over during the operation preceding, this routine is terminated without further processing because the remaining hydrocarbons in adsorbent 16 could prevent a adequate determination of adsorbent deterioration 16.

On the other hand, if the result of the determination in step 61 is YES, indicating that the hydrocarbons have been desorbed during the preceding operation, it is determined whether deterioration determination enable flag F_MCND it is or not "1" (step 62). The enable flag of Determination of impairment F_MCND is set to "1" in the assumption that adsorbent 16 can be determined correctly with respect to deterioration when the engine water temperature TW is greater than a predetermined value (for example, 85 ° C), it is that is, adsorbent 16 has been heated to a temperature at which adsorbed hydrocarbons can be desorbed, and a mixture of air / fuel supplied to engine 1 has remained within a predetermined range near the stoichiometric ratio of air / fuel for a predetermined time or more during a engine operation 1. Therefore, if the result of the determination in step 62 is NO, that is, when F_MCND = 0, this routine is terminated without additional processing because you cannot make an appropriate determination of the deterioration of the adsorbent 16.

If the result of the determination in step 62 is YES, that is, when F_MCND = 1, it is determined if the difference between the water temperature of the TW motor and the ambient temperature TA is greater than a predetermined DT value (step 63). If he result of the determination in step 63 is YES, that is, when TW-TA <DT (at time t2 in Figure 13), the UEC 25 calculates a determination value VHUMD_JUD2 to determine a deterioration of adsorbent 16 looking for a table, not shown, according to the water temperature of the TW motor in the event that the TW engine water temperature has cooled to a temperature substantially equal to room temperature TA, that is, the adsorbent 16 has cooled to a substantially equal temperature at room temperature TA, and room humidity VHUMD remains substantially constant, that is, in the regime state (step 64). The determination value VHUMD_JUD2 is set to a value lower when the temperature of the TW motor is lower.

In the next step 65, it is determined whether or not the ambient humidity VHUMD is equal to or less than the determination value VHUMD_JUD2. If the result of the determination in step 65 is YES, that is, when VHUMD \ leq
HUMD_JUD2 (for example, curves a, b in Figure 13), the ECU 25 determines that the adsorbent 16 still has a high moisture adsorption performance and therefore is not deteriorated, and sets the FTRSDT deterioration flag to "0 "to indicate (step 66), followed by the completion of the routine.

On the other hand, if the result of the determination in step 65 is NO, that is, when VHUMD> VHUMD_JUD2 (for example, a curve c in Figure 13), the UEC 25 determines that adsorbent 16 has a low yield of moisture adsorption and therefore is impaired, and puts the FTRSDT deterioration indicator to "1" (step 67), followed by the Routine completion.

If the result of the determination in step 63 is NO, indicating that TW? TADT, that is, when the adsorbent 16 has not cooled to a temperature substantially equal to the ambient temperature TA, ECU 25 increases a counter C_DONE indicative of the number of times the determination of deterioration (step 68), assuming that VHUMD ambient humidity is not in the regime state, and it is determined whether the indicated value by the counter C_DONE is or not equal to or less than a limit value upper N (step 69). The counter C_DONE is initialized to "0" when engine operation is stopped 1.

If the result of the determination in step 69 it is YES, that is, when C_DONE \ leqN, the ECU 25 establishes again the time in the idle timer used to return to start UEC 25 after the default stop time of motor 1 in an additional time \ Deltat (for example, 30 minutes) shorter than the default time (step 70), followed of the completion of the routine. In this way, the determination of deterioration is interrupted once, and resumes after the course of additional time \ Deltat when UEC is restarted 25. The value in the counter C_DONE is maintained during the interruption. Then, if the result of the determination in step 63 changes to YES in the determination of resumed deterioration, they are executed consequently steps 64 onwards.

On the other hand, if the result of the determination in step 63 is still NO even after the Determination of resumed impairment, and whether the result of the determination in step 69 is also NO, that is, when the TW motor water temperature does not converge to temperature TA environment even after the summation (time default) of the default time originally set in the idle timer and a time corresponding to upper limit value N (= Nx \ Deltat) after stopping the motor 1 (at time t3 in figure 13), as indicated by a dashed line d in figure 13, this routine is terminated in the assumption that an impairment determination cannot be made of adsorbent 16. The upper limit value N and time t3 are set based on predetermined and analogous experiments, and the time t3 is set, for example, to 24-72 hours.

As described above, the Determination of deterioration for adsorbent 16 in the third realization is done during a period in which the ambient humidity VHUMD detected by the humidity sensor located upwards 30 is in the steady state after stopping engine 1 (between times t2-t3 in figure 13). Therefore, the Determination of impairment can be done properly and with precision with respect to adsorbent 16, as described previously. In addition, since the determination of impairment only requires the detection of ambient humidity in the state of regime, a humidity sensor to detect ambient humidity not it has to have a high sensitivity, so that it can be used a reasonable humidity sensor, thereby reducing the cost of general apparatus

In addition, the determination of impairment is made in the condition that engine 1 has been running near the stoichiometric air / fuel ratio before standing. In In general, when the engine 1 starts running near the stoichiometric air / fuel ratio, exhaust gases they contain a relatively large amount of moisture without large variations, so that the ambient humidity VHUMD immediately after stopping engine 1 it is also relatively high without large variations, suitable for carrying out the determination of deterioration of the adsorbent 16. Thus, the determination of deterioration made in such condition can provide one more determination Exactly on whether adsorbent 16 is damaged.

It should be understood that the present invention does not is limited to the aforementioned embodiments, but it can be Implement in several ways. For example, although embodiments employ the relative humidity VHUMD and the value of VRST sensor resistance as parameters indicative of humidity of exhaust gases, any other can be used instead appropriate parameter. In addition, in the aforementioned embodiments, the temperature status in the exhaust system 2 is represented by the TW engine water temperature detected by the engine water temperature 23, and THCM ambient temperature around the humidity sensor located down 22 is detected directly by the room temperature sensor 21. Alternatively, they can be estimated based on a detection value of the humidity sensor located down 22.

In addition, in the third embodiment, the sensor upward humidity 30 is used to prevent disturbance such as a gas exchange between the environment of the bypass passage 14 and external air when ambient humidity VHUMD is detected after stopping the engine 1. Alternatively, the humidity sensor located down 22 can be used to detect Ambient humidity Otherwise, the configuration details can be modified as appropriate without departing from the scope of the invention defined in the appended claims.

As described above in detail, the state determining apparatus for a gas purifier of exhaust can advantageously determine, with great accuracy, the state of the exhaust gas purifier including an adsorbent to adsorb hydrocarbons, including deterioration of the adsorbent, according to a temperature state of an exhaust system in an engine Internal combustion

A device for determining state for an exhaust gas purifier to determine with precision state of the exhaust gas purifier including a adsorbent to adsorb hydrocarbons, including deterioration of adsorbent, according to a temperature state in an exhaust system of an internal combustion engine. The apparatus for determining state for an exhaust gas purifier is arranged in a internal combustion engine exhaust system to determine the state of the exhaust gas purifier including the adsorbent capable of adsorbing hydrocarbons and moisture in exhaust gases. He status determination device includes a humidity sensor arranged near the adsorbent in the exhaust system to detect moisture inside a bypass exhaust pipe, and an ECU to determine a temperature status of the exhaust system and determine the state of adsorbent according to the humidity inside the tube bypass leakage detected by the humidity sensor and the temperature status in the exhaust system detected by the ECU

Claims (13)

1. A state determination apparatus for a exhaust gas purifier (6) arranged in an exhaust system of an internal combustion engine (1) to determine a state of said exhaust gas purifier (6) including an adsorbent (7) capable of adsorbing hydrocarbons and moisture in exhaust gases, including said state determination apparatus: a humidity sensor (22) arranged near said adsorbent in said exhaust system (2) to detect a moisture in an exhaust pipe (4) of said exhaust system; temperature sensing means (23) to detect a temperature state (TW) in said system of escape (2); Y adsorbent state determination means (25) to determine a state of said adsorbent (7) according to the moisture in the exhaust pipe (4) detected by said sensor humidity (22) and the temperature state in said exhaust system detected by said means temperature status detectors (2. 3). 2. A state determination apparatus for a exhaust gas purifier according to claim 1, including also means of calculating calories (25) to calculate calories supplied from said internal combustion engine (1) to said exhaust system (2) after starting said combustion engine internal (1), where said means of determining status of adsorbent (25) further determine the state of said adsorbent (7) also according to the calories calculated by said calculation means of calories (25). 3. A state determination apparatus for a exhaust gas purifier according to claim 2, including also: threshold determination means (25) for determine a threshold (TRSDT) based on the temperature state in said exhaust system (2) detected at the time of starting said internal combustion engine (1), where said calculation means of Calories (25) include means for calculating injection quantity of accumulated fuel to calculate a quantity of fuel accumulated (sum_tout) supplied to said combustion engine internal (1) from its start as said calorie, and said means for determining status of adsorbent (25) determine the state of said adsorbent (7) on the basis to a result of comparison between the amount of fuel accumulated (sum_tout) from the start of said combustion engine internal (1) and threshold (TRSDT) when a change amount of value detected by said humidity sensor (22) after starting of said internal combustion engine (1), exceeds one default value set. 4. A state determination apparatus for a exhaust gas purifier according to claim 1, including also: ambient temperature detecting means (21) to detect an ambient temperature around said sensor moisture (22); Y relative humidity calculation means (25) for calculate a relative humidity (HVUMD) of exhaust gases from an outlet of said humidity sensor (22) according to the temperature environment detected. 5. A state determination apparatus for a exhaust gas purifier according to claim 1, wherein said humidity sensor (22) is arranged in a position towards below said adsorbent (7) in said exhaust system (2). 6. A state determination apparatus for a exhaust gas purifier according to claim 1, wherein said adsorbent state determination means (25) determine the state of said adsorbent (7) after a stop of said internal combustion engine (1). 7. A state determination apparatus for a exhaust gas purifier according to claim 6, wherein said adsorbent state determination means (25) determine the state of said adsorbent (7) within a period predetermined after stopping said combustion engine internal (1). 8. A state determination apparatus for a exhaust gas purifier according to claim 6, wherein said humidity sensor (22) is arranged in a position towards above said adsorbent (7) in said exhaust system (2). 9. A state determination apparatus for a exhaust gas purifier according to claim 6, including also: operating condition detecting means for detect if said internal combustion engine (1) is set to operation or not in a predetermined operating condition before of stopping said internal combustion engine (1), where said means of determining status of adsorbent (25) determine the state of said adsorbent (7) when said operating condition detecting means (25) detect that said internal combustion engine (1) is put into operation in said predetermined operating condition before the stop of said internal combustion engine (1). 10. A state determination apparatus for a exhaust gas purifier according to claim 9, wherein said predetermined operating condition of said motor of internal combustion (1) is a condition in which a mixture of air / fuel supplied to said internal combustion engine (1) is at an air / fuel ratio near the ratio stoichiometric air / fuel during the operation of said internal combustion engine (1). 11. A state determination apparatus for a exhaust gas purifier according to claim 1, wherein said temperature state of said exhaust system (2) is a temperature (TW) of the cooling water at the start of said internal combustion engine (1). 12. A state determination apparatus for a exhaust gas purifier according to claim 1, wherein said adsorbent state determination means (25) include Adsorbent deterioration determination means to determine a deterioration of said adsorbent (7) as the state of said adsorbent. 13. A state determination apparatus for a exhaust gas purifier according to claim 1, wherein said adsorbent (7) includes zeolite.